The separation of very fine solid particles of a size of roughly 0.5 to 5 μm from liquid suspensions by sedimentation normally requires very long sedimentation times as the settling rate of the particles is very slow. This means that the particles must not be influenced by the flow of the liquid during sedimentation, which in practice means that effective sedimentation can be carried out only in a stationary liquid mass, as the particles are influenced by nothing other than the forces of gravity.
SE-B-7509004-3, for example, describes an arrangement of the type described in the introduction for separating a lighter liquid phase together with heavier solid fractions from a heavier liquid phase of a liquid mixture. Such an arrangement would not, however, be capable of or suitable for continuous separation of very fine solid particles which are difficult to separate of the type referred to above on account of excessive disturbance caused by the liquid suspension flowing through.